What is the process flow of sheet metal painting?

[AllieMarie]

Remove the damaged sheet metal parts of the collision vehicle from the original body by means of cutting. Grind the original paint of the damaged area until the iron plate layer is exposed. Eliminate the tensile and compressive stresses generated during the process of restoring the metal to its original shape and thickness through heat treatment. Sand the area to be painted with sandpaper and apply clear paint.

[Chloe]

I've seen many cars come into the shop for repairs, and the sheet metal painting process mainly consists of seven steps: First, use professional tools to pull and flatten the deformed parts back into position, then use a grinder to remove the old paint layer, exposing the shiny metal surface. The second step involves applying body filler to the metal surface to fill in dents—this step particularly tests the technician's skill, requiring it to be as smooth as a plasterer smoothing a wall. After the body filler dries, the third step begins—fine sanding, which involves repeatedly hand-sanding with different grades of sandpaper until the surface can reflect light. The fourth step is the crucial rust prevention treatment, spraying epoxy primer on the exposed metal areas, which forms a protective layer after baking. The fifth step is applying the color paint, with most shops now using computer color matching to ensure it matches the original car paint. This step must be done in a dust-free paint booth, or dust settling on the paint surface would ruin everything. Immediately after applying the color paint, a clear coat is sprayed on top to form a crystal-clear protective layer. Finally, the car is sent into a baking room for half an hour of high-temperature baking to cure the paint. After completion, the transition areas are polished to ensure a natural blend between the new and old paint. The entire process takes at least two days, with more extensive repairs even taking up to a week.

[VonElliana]

Last time my car got scratched, I took it for bodywork and painting, and the whole repair process was quite meticulous. The technician first used a hydraulic press to pop out the dent on the door, then inspected every inch of the steel panel with a magnifying glass equipped with a light. When applying putty, I saw him use a special spatula to press it back and forth over a dozen times—his focus was like that of a jade carver. The painting stage was even more interesting: the technician wore a full-body protective suit, keeping the spray gun about 20 centimeters from the car body while moving at a steady pace without even a tremble in his wrist. The heat inside the paint-drying booth was intense—the freshly painted car being wheeled in felt like entering a sauna. But what surprised me most was the post-painting process: after the paint cooled, it had to be polished three times with rubbing compounds—first using coarse wax for overall sanding, then fine wax to address orange peel texture, and finally mirror-finish wax for hand polishing. The whole workshop smelled of paint thinner, but seeing the repaired paint job reflect like a mirror made it all worth it. Remember, this level of professional craftsmanship takes at least three days to fully cure.

[OFrank]

The technical essence of automotive sheet metal and painting lies in metal restoration and color matching. The sheet metal process involves using a metal straightening machine to repair the vehicle frame, while complex curved surfaces require localized shaping with an aluminum panel repair machine. The key to paintwork lies in the four-layer structure: phosphating primer for corrosion prevention, epoxy primer to fill pinholes, the basecoat layer determining color saturation, and the clearcoat providing hardness protection. Nowadays, high-end repairs utilize water-based paints, which are more environmentally friendly than traditional solvent-based paints but more challenging to apply—spray gun speed must be controlled at 0.5 meters per second, with each paint layer thickness precisely maintained at around 15 microns. The baking process is even more meticulous: infrared lamps must maintain a distance of over 80 cm from the surface while moving, with temperature controlled in stages—60°C for 20 minutes preheating, 80°C for 30 minutes curing, followed by natural cooling to 40°C before leaving the booth. To inspect craftsmanship quality, a thickness gauge is used for point measurements on repaired areas—paint thickness deviations exceeding 30 microns are considered substandard.

[Lorenzo]

New car owners need to know this: Sheet metal repairs cannot restore the steel panel to its factory condition, just like a crumpled piece of paper will always show creases no matter how much you smooth it out. The most critical part of painting is the pre-treatment. If the old paint isn't thoroughly sanded off or if there's grease residue, the new paint will quickly bubble and peel. Nowadays, reputable repair shops will wipe down the entire car with silicone remover before painting to prevent polishing compound residues from affecting adhesion. During the color-matching stage, technicians use a spectrophotometer to compare against the factory color code. However, for cars older than five years where the original paint has oxidized, the new paint usually needs to be mixed half a shade brighter to achieve visual matching. After baking, pay special attention when inspecting edges and crevices, as these areas are most prone to runs or overspray. A reminder to everyone: don't rush to wash your car immediately after painting - it's best to wait 7 days for the paint to fully cure before exposing it to high-pressure water jets. Also, promptly clean off mud and road spray from rainy driving, as the freshly repaired paint surface is particularly vulnerable to corrosion from alkaline mud.

[LunaRose]

From the perspective of vehicle value retention, choosing OEM-certified repair shops for bodywork and painting is the best option. The water-based paint they use costs three times as much as regular paint, but its aging resistance index is over 50% higher. Sheet metal repair isn't just about hammering the steel panels flat; it also involves restoring the body's rigidity coefficient using resistance welding. Nowadays, standard repair procedures include paint film strength testing, where the surface must show no marks when scratched with a pencil hardness tester to pass. Special attention should be paid to areas like sunroof edges, as regular shops might skip anti-corrosion treatments, while certified shops apply PVC sealant. Upon completion, check the quality inspection sheet to confirm three key metrics: sheet metal flatness error ≤ 1mm, paint color difference ΔE ≤ 1.5, and clear coat hardness ≥ 2H. Although this level of craftsmanship may cost around 1,000 yuan more, it ensures no cracking or fading within five years and won't affect used car valuations. Additionally, repair shops offering lifetime warranties will redo peeling paint free of charge.